MicroRNAs are typically small RNA molecules of generally about nineteen to twenty-five nucleotides in length. These microRNAs are non-coding RNAs which are cleaved from hairpin precursors. Several microRNAs have been identified in the genomes of a wide range of multicellular life forms.
Many microRNAs are conserved in sequence between distantly related organisms, and exhibit tissue-specific or developmental stage-specific expression. The conservation of the sequence between organisms indicates that microRNAs may play important roles in biological processes.
MicroRNA molecules have been reported to control gene expression in a sequence specific manner in a wide variety of organisms by blocking translation after partially hybridizing to the non-coding 3′ region of mRNAs of target genes. The genes targeted by microRNAs largely remain to be characterized.
However, there is growing evidence that microRNAs are implicated in various diseases and illnesses. For instance, drosophilia microRNAs have been shown to target genes involved in apoptosis. Also, B-cell chronic lymphocytic leukemia has been linked to the deletion of two microRNAs.
Pancreatic islet cells (also referred to as islets of Langerhans) are groups of specialized cells that make and secrete hormones. It is reported that there are five types of cells in an islet: alpha, beta, delta, PP and D1 cells.
Some of these cells are said to be involved in the regulation of glucose. For example, alpha cells secrete glucagon which are hormones involved in raising the level of glucose in the blood. Further, beta cells secrete insulin, a hormone that helps the body utilize glucose for energy.
Interference in the regulation of glucose utilization, particularly of the insulin-secreting beta cells, may lead to diseases and illness such as diabetes. Therefore, it is important to elucidate the mechanisms involved in mediating genes which play a role in the regulation of glucose homeostasis. For example, it is not known in the prior art whether microRNAs, if present, mediate glucose utilization.
Thus, there is a need for materials and methods that can help elucidate the function of regulators, such as microRNAs, of pancreatic islet cells.
Further, due to the ability of microRNAs to induce RNA degradation or repress translation of mRNA, which encode important proteins, there is also a need for novel molecules that inhibit pancreatic microRNA-induced cleavage or translation repression of target mRNAs.